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Discussion Starter · #1 ·
We are converting a 4x4 offroad racecar to electric drive, we used a 2015 Nissan Leaf as a donor. So we are using that motor, and are making the modules from that battery work, but we need more capacity. So we are buying a 62kwh pack.

My question is if the dimensions of the individual modules of the 62kwh pack have similar dimensions to the 24kwh versions. Also, if anyone has any insight on how to get this thing wired up, I'm all ears. We are in the Bay Area, need all the help we can get.
 

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IIRC, the modules for 24kWh was arranged in 2S2P, but for the 62kWh it was 2S4P.

Not sure if it'll be considered double the thickness, but at the very least my guess it won't be similar
 

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Discussion Starter · #3 ·
IIRC, the modules for 24kWh was arranged in 2S2P, but for the 62kWh it was 2S4P.

Not sure if it'll be considered double the thickness, but at the very least my guess it won't be similar
If they are thicker, that’s okay. What I’m looking for is the dimensions of the holes that run through
 

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The modules used for the Leaf's 24 kWh, 30 kWh, and 40 kWh packs are identically configured (48 modules in series, 2S2P modules, so 96S2P overall, physically stacked in the same orientations and locations). The modules used for the Leaf's 62 kWh pack are completely different, with 16 modules of three different stack lengths for an overall 96S3P. The outer pack case shape is essentially the same, but deeper for the 62 kWh pack (so it hangs lower below the car), but everything inside is arranged and constructed completely differently.

If you're using the complete pack in its case, the 62 kWh pack could replace any of the other packs if you have some extra height. If you're using the modules from within these packs, there's no similarity and you're starting again in pack design.

An informative link (including images of both old and new packs):
 

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The 62kWh modules look very suspiciously like they have the same bolt hole configuration. You'll have to find a measurement to be sure...24kWh module has top holes 190mm apart, bottom holes 160mm apart, and the top and bottom holes are 275mm apart (this was just a quick tape measurement)

That said, the connection points are wildly different. I'm not sure you could build an enclosure that would work for both, but I dunno. It doesn't seem like the 62kWh modules can be stacked on one another unless disassembled to the cell level.
 

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The 62kWh modules look very suspiciously like they have the same bolt hole configuration. You'll have to find a measurement to be sure...24kWh module has top holes 190mm apart, bottom holes 160mm apart, and the top and bottom holes are 275mm apart (this was just a quick tape measurement)
Possibly, but while the original modules were in 6 vertical stacks and one horizontal stack, the new ones are in 16 vertical stacks, so while front-to-back hole spacing in the vertical stack (presumably the 160 mm and 190 mm dimensions , although they would be "front" and "back" rather than "top" and "bottom" in a horizontal stack as it is oriented under the back seat of a Leaf) could reasonably match, side-to-side spacing in the vertical stack (the 275 mm dimension) seems unlikely to match.

Is this what you mean by those dimensions?
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It doesn't seem like the 62kWh modules can be stacked on one another unless disassembled to the cell level.
I agree; these are like most pouch cell modules now - they can be stacked to any desired length if the welded cell-to-cell and end cell-to-module-terminal connections are modified, but just putting one stack on top of another would require some interesting structure between modules.
 

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Possibly, but while the original modules were in 6 vertical stacks and one horizontal stack, the new ones are in 16 vertical stacks, so while front-to-back hole spacing in the vertical stack (presumably the 160 mm and 190 mm dimensions , although they would be "front" and "back" rather than "top" and "bottom" in a horizontal stack as it is oriented under the back seat of a Leaf) could reasonably match, side-to-side spacing in the vertical stack (the 275 mm dimension) seems unlikely to match.
From the illustrations of pack buildup, it does seem unlikely, yes. They do seem similar, and the reasoning for the positioning of the holes is the same, but I'm not sure whether it's the same pouch cells being used. Sadly my japanese is not good enough to see that from the pictures at insideevs.

Regarding how this is supposed to be connected up, so far I have not seen any documentation on HOW this is connected in the Leaf pack. Presumably, since all the stacks contain a number of cells divisible by 3, it's three in parallell directly on top of each other, and then either 4, 7 or 9 of those in series in a stack. Even the production video jumps straight from testing individual cells to plugging stacks together.

Interestingly enough, NOONE has actually documented taking one apart yet. Just seeing one of those stacks without the black plastic cover would be very insightful.
 

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Discussion Starter · #9 ·
Great discussion

Tremelune, I agree the bolt holes look suscpisiously the same, no doubt at least similar. It is pretty apparent they have the same general design where the bolts pass all the way through. If this is the case, it should work for my current pack design, as long as they are under 10 inches wide or so.

olegil I totally agree with your presumptions of the cell configuration. My main worry is also how the cells are specifically attached. Laser welding is mentioned in the marketing materials, this is an indication that whatever is behind that black plastic might not be easy to connect to a common BMS so that I could use older and the new style in the same car. But if I can somehow get connections onto each of the 96 cells I should be good.

I am attempting to purchase a 62kwh, hopefully it will be on the way to me shortly I will share what I find on teardown.

Heres what I got so far, still sort of evolving. Hoping the high capacity cells will fit in the racks I've built, or at least I can make a new rack that will work with the rails I've got, So i can keep it all interchangable between high and low capacity packs.
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Regarding how this is supposed to be connected up, so far I have not seen any documentation on HOW this is connected in the Leaf pack. Presumably, since all the stacks contain a number of cells divisible by 3, it's three in parallell directly on top of each other, and then either 4, 7 or 9 of those in series in a stack.
Yes, that makes sense. If those are the right stack heights, then
  • 1 row of four 7S modules under the front seats: 1 x 4 x 7 = 28 cell groups in series
  • 2 rows of four 4S modules under the rear footwell: 2 x 4 x 4 = 32 cell groups in series
  • 1 row of four 9S modules under the rear seat: 1 x 4 x 9 = 36 cell groups in series
  • Total 96 cell groups in series

My main worry is also how the cells are specifically attached. Laser welding is mentioned in the marketing materials...
Pouch cell tabs are normally welded (ultrasonically, or perhaps laser) to connecting bars. People modifying modules using similar cells have had some success removing welds, and making new connections with bolts and nuts.
 

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... I agree the bolt holes look suscpisiously the same, no doubt at least similar. It is pretty apparent they have the same general design where the bolts pass all the way through. If this is the case, it should work for my current pack design, as long as they are under 10 inches wide or so.
The old modules are in four stacks on each side, short module side front-back in the car, plus a horizontal stack with the long module side front-back in the car. The new modules are in four rows of stacks, with the long module side front-back in the car. So four times the new long side roughly equals four times the old short side plus one long side.

The old modules are 303 mm by 223 mm, so the total of the modules front-to-back is 4 x 223 + 303 = 1195 mm. Since the new modules are little more tightly packed in the case that means that the new modules are at least 1195 / 4 = 299 mm long... they might be the same length as the old modules.

But your concern is not this dimension, but the shorter cell side and resulting module width. Four modules just barely fit within the internal width of the battery case, so as long as that internal width is less than 40 inches, the modules will be less than 10 inches wide. The width of the old modules is unrelated, but happens to be 223 mm, or 8.8".

Rather than reconfiguring modules, given the rack design it would make more sense to me to use the new modules separately, with minimal spaces between them in the rack.For the entire 62 kWh pack to fit, each of the four racks would need to hold one 7S3P module, two 4S3P modules, and one 9S3P module... just like one of the four front-to-back rows of the original Leaf pack, but with the modules turned on their sides.
 

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We are converting a 4x4 offroad racecar to electric drive, we used a 2015 Nissan Leaf as a donor. So we are using that motor, and are making the modules from that battery work, but we need more capacity. So we are buying a 62kwh pack.
I'm going to ask a question on your initial problem, which might be sensitive so please feel free not to reply if you don't want to answer haha.

looking at the pictures you posted, it seemed like you were originally comfortable in using the 30kWh pack from the 2015 Leaf without any plan for any increase in capacity, going as far as to building the frames to hold only those modules and nothing else

Only at this time then you realized that it wasn't enough, and you need to change/add the 62kWh modules inside. So now you're faced with a problem on how to manage the dimensions and whether you need to build a new frame etc.

My questions is: what caused the change in this decision? was it an initial assumption on your usage which you thought you wouldn't need such high capacity, but in the end you realized otherwise? Or was it an initial space constraint that is now slightly bigger so you can afford to squeeze in more modules? or...?

I'm hoping your answer will help other members avoid such a scenario in the future of having to rebuild their packs halfway through the conversion
 

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Discussion Starter · #13 ·
ishiwgao Great question, certainly no offense taken this is an open discussion where anything relevant goes.

I'm really into rock crawling. It's super fun. Very technical driving, thats slow paced so for the most part there is low risk of injury while still keeping the adrenaline up. I had a solid axle swapped 1989 Toyota 4runner, locked differentials with lower gears, chromoly axles and 39" tires. It is great fun to go for a camping/wheeling weekend where you basically drive on trails, drink beer eat food and talk shit all day and night.

Part of going off roading with decades old, beat up and neglected trucks is that they are pretty much always on the verge of breaking down for lots of reasons. I think an electric motor and batteries, after a few bugs are worked out, will be significantly more reliable than the old Toyota ICE and supporting systems. More time having fun, less time broken on the few weekends a year we get together.

Rock crawling specifically is also well suited to electric drive, where low end torque is desired over sustained high output. You can have fun all day in a rock crawler and never go farther than a 5 mile radius from camp or go over 20 mph.

So I've been talking/dreaming about it for years, and finally overheated my motor earlier this year and its not worth repair. Lots of thought/research, including guidance from this site, plus budget constraints led me to the Leaf components. A running driving Leaf could be had in the ~$3500 range, which would yield a motor and batteries. Thunderstuck has the Leaf VCU for $500, and I knew there would be more components to buy but I figured this was the most economical way to get my 'runner de-ICEd with a modern, powerful AC motor(regen) with Li-ion batteries. I knew the capacity wouldn't be great, but I decided it was a compromise I was willing to take for now. The idea being get the thing running and driving, and in time upgrade the batteries. So I bought a donor September '20, a 50k 2015 Leaf salvage title running and driving for $4000 and started collecting parts.

Then I got a call that there would be a new EV only class at the February 2021 King of the Hammers event. KOH is the largest rock crawling event in the world, over 50,000 attend annually for a week of racing in the So Cal desert.
Element of Survival is a really cool video to watch to get an idea of the cars and terrain, lots of other videos documenting the race can be found easily.

That's when the plan changed, I knew I had to compete. A team was made of coworkers, friends and family. We don't have time to turn my beat up Toyota into a racecar due to what's required for safety. A friend who had an old 4600 class 4runner racecar that has previously competed in KOH offered his chassis to convert. So I sold my crawler and am all in on converting this car.

The challenge is a ~90 mile loop, with 2 pit stops. There will be about a 20 mile section, pitstop, 45 mile section, pitstop, and a third ~20 mile section. It will include steep sandy hills, rock crawling, and long straight flats. The 24kwh pack that came in the car will not be anywhere close to accomplishing this. We decided swapping discharged batteries for charged ones at pit is how we will tackle the problem. Based on napkin math, two fully charged 24kwh packs cannot be relied upon to take the vehicle 45 miles. So we need to used the later model higher capacity packs. Sticking with Leaf modules because I've already invested in the Dilithium 96 cell BMS and am somewhat comfortable with them. I like the simplicity of the aircooled design, even though it compromises performance.

The late model packs are hard to find. I found a salvage yard that has a 40 and a 62, and they are charging the same price. I know the 40 will bolt into what we built, but I couldn't bring myself to pay the same price for ~50% less capacity. I am also actively searching for two more packs, ideally 1 40kwh and 1 24kwh. That would give us lots of battery options, and those packs would have basically no more unknowns when it comes to packaging/wiring. Also, after the race, the loose plan is to get myself another rock crawler chassis, another Leaf motor, and split the batteries between the two vehicles, on an agreement that owner of this car will purchase the batteries/electronics that stay in his car.

That pretty much brings this story up to date. It has defiantly been an evolution. Ideally there would have been a clear goal, component list and execution plan from the outset, but that's not how this one is working out. Have learned alot so far, looking forward to the real-world data of EV energy consumption in a 4x4 vehicle that weighs 5000lbs+ with 35 inch offroad tires traveling some of the gnarliest terrain in the world.

62kwh pack ships today from Tennessee to California, cant wait to get it here and tear it down.

Pictures of Hammertown and race action on the trail Backdoor, roughly 2015 perhaps earlier.
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That's a great story of how the project came to be. It explains the reason for the pack design, in what are obviously intended to be readily removable modules. It also explains why what I was assuming was a pickup truck had a strange cab rear wall and very strange cage - there was no cab rear wall and the cage continued over the back seat because it was a first-generation 4Runner! I'll admit that I had not noticed the drop in the floor for the back seat.
 

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Agree with brian_, that was very well written out, and a really interesting story.
I hope you'll be giving us feedback, measurements and pictures of the breakdown as soon as you can. Could be very useful to the next guy.
From what we can tell so far, it does seem like the modules you find in the 62kWh will at least be similar lengths and widths, even if they might not be identical. I don't see ANYTHING that would indicate they're using a different pouch cell, the move from 40 to 62kWh can easily be explained by the move from 2P to 3P configuration (the lower peak drain from each cell resulting in less loss in internal resistance could give the extra bonus capacity).
So good luck, have fun and stay safe.
 

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Discussion Starter · #16 ·
Got the 62kwh pack in this week.
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Got the individual modules out
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Here's what's behind the black plastic:
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The modules are made of what is essentially the same cell, it does have slightly different molding on the edge but the dimensions are about the same.

I am not going to break down the modules. It looks like it would be tough to get it all reassembled with similar reliability and energy density. I am going to cut and splice into the existing bms wires that are already sticking out of the modules, and set them up in frames similar to what I've done with my 24kwh pack.

Let me know if there are any specific questions or pictures you would like.
 

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Got the 62kwh pack in this week.
Great detail photos! :)

I am not going to break down the modules. It looks like it would be tough to get it all reassembled with similar reliability and energy density.
The biggest problem would likely be electrical connections to the cell tabs. Those are interesting welds...

I am going to cut and splice into the existing bms wires that are already sticking out of the modules, and set them up in frames similar to what I've done with my 24kwh pack.
Sounds good. Have you measured the heights of the modules to determine the total length of each of the four stacks that you are assembling? Presumably it's longer than the current stacks of 12 modules each.
 
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